Propeller hub structure



Aug. 14, 1956 E MARTlN ETAL PROPELLER HUB STRUCTURE Filed Dec. 28, `1955 United S'tates Patent O PROPELLER HUB STRUCTURE Erle Martin, West Hartford, and Raymond P. Lambeck,

Manchester, IConn., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application December '28, 1953, Serial No. 400,738

l12 Claims. (Cl. Utl-16.0.32)

This invention relates to hydraulically actuated aeronautical propellers and particularly to means for lubricating the blade mechanism without subjecting the propeller hub to excessive pressures.

An object of this invention is a hydraulically actuated propeller having only two fluid lines leading to the propeller and utilizing the pitch changing operating lluid for lubrication of the blade bearings and pitch change gears in the interior of the hub in which means are provided preventing the application of the full operating pressure to the hub interior.

A further object of the invention is a hydraulic propeller in which the hub interior is sealed from the doubleacting pitch changing motor and valve mechanism is provided for automatically connecting the inoperative side of the double-acting pitch changing motor with the hub interior.

A still further` object is the provision of a shuttle valve actuated by the pitch changing motor actuating uid for blocking the motor actuating lluid from the hub interior and connecting the inoperative side of the motor with the hub interior.

Other and additional objects will be apparent from the following specication and the accompanying drawings in which:

Fig. l is a side elevation with parts broken away, showing a propeller with the lubricating shuttle valve.

Fig. 2 is an enlarged view of the pressure actuated shuttle valve of Fig. 1.

Fig. 3 is a section in line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 2 but showing the valve in its other position.

In hydraulically actuated aeronautical propellers it has been customary 4to lubricate the blade retaining bear- 'ings and the blade drive gears by the hydraulic lluidused to actuate the pitch changing motor. In small sizes and when the actuating lluid does not reach very high pressures, it has been possible to make barrels which could stand the lluid pressure and it has been possible to seal the barrels so that no material leakage would take place. However, with the advent of larger barrels and higher operating pressures it has been found that the sealing problem becomes acute and the barrels cannot be properly sealed to retain the full operating pressure applied to the hydraulic pitch changing motors. In addition the high oil pressure in the hub barrel places an additional load on the barrel structure which can be avoided by the use of the lower pressures.

The present invention relates to mechanism for utilizing the hydraulic pitch changing lluid of a double-acting pitch changing motor for lubricating the blade bearings and drive mechanism but preventing the application of the high pressure lluid to the interior of the barrel. In order to accomplish this the hub or barrel has been sealed olf from the pitch changing motor and a separate Vlubricating -line led from the motor feed lines to the barrel interior. A valve actuated by the pressure of the pitch changing lluid is inserted in the line leading to the 2,758,659 Patented Aug. 14, 1956 'ice interior of the barrel and is actuated by the pitch changing lluid to block pitch changing iluid from the barrel interior and simultaneously connect the barrel interior with the drain or low pressure side of the pitch changing motor.

ln the propeller structure shown in the drawing, which is a well-known propeller construction, such as is shown in Patents Nos. 2,280,713 and 2,280,714 and is chosen for the purpose of illustrating the invention. As this type of propeller is now well known it will be very brielly described, further details may be obtained from the cited patents. A propeller indicated generally at 10 mounted on a shaft 12 is driven by an engine 14. The propeller has a hub or barrel 16 supporting blades 18 and 20 on retaining bearings 22 and is driven by a spider 24 having arms 26 extending into the blade interior and mounted on the propeller shaft 12 and driven by splines 28. A dome 30 is secured to the outboard side of the barrel 16 and acts as a cylinder for the pitch changing piston 32 which carries the cam follower 34 through oppositely directed cam slots 36 and 38 in the stationary cam sleeve 40 and the movable cam sleeve 42, respectively. Movable cam sleeve 42 carries bevel gear 46 at one end thereof which gear meshes with gears 48 on the several blade ends. Reciprocating movement of the piston 32 in the cylinder 30 will rotate cam sleeve 42 and thus rotate blades 18 and 20 to change their pitch. A tube 50 is led through the center of the piston for conducting actuating fluid from the propeller shaft 12 to the front side or outboard side of the piston. A packing 52 seals the piston 32 with respect to the cylinder 30 and a packing S4 seals the piston 32 with respect to the tube 50.

A valve housing 56 having lluid distributing passages therein is threaded into the interior of propeller shaft 12 and seats on a gasket 5S against the closed end 60 of a pair of sleeves, 62, 64 fixed in the propeller shaft 12 and forming an annular fluid passage 66 surrounding a central fluid passage 68. The interior of the hub 16 is sealed from the inboard end of the piston 32 and the open end of cylinder 30 by a series of packings or seals including a seal 70 between the barrel 16 and the in board end of cylinder 30, a seal 72 between the inboard end of cylinder 30 and the stationary cam sleeve 40, a seal 74 between the stationary and rotatable cam sleeves 40 and 42 and a seal 76 between retaining nut 78 and a sleeve secured in fluid tight relation to the movable cam sleeve 42 and a seal 82 between the retaining nut 78 and the valve housing 56. The packing 58 seals the inboard end of valve housing 56 from the interior of propeller shaft 12 at the interior of the propeller hub. The propeller hub interior is thus sealed from the pitch changing motor so that luid applied to the rear of the doubleacting motor does not nd a ready access to the hub interior.

Fluid is fed to the pitch changing motor from the engine lubricating system comprising an engine oil reservoir and the engine lubricating pump 84 having the usual relief valve 86 for maintaining a limited pressure on the lubricating fluid. Engine oil is led through the conduit 88 to a double-acting governor 90 which may be of any well-known type such as is shown in Patent No. 2,402,065. This type of governor is now well-known and will be only briefly described here, further details may be obtained from the cited patent. This governor includes the usual yweights 92 acting against a spring 94 for moving a pilot valve 96 in overspeed conditions to connect line 98 with the high pressure output of pump 100 appearing in chamber 102, and the line 104 with engine oil pressure appearing in line 83 which is also the inlet to pump 100. The governor acts to substantially block lluid flow for onspeed conditions and in underspeed conditions connects line 104 with the high pressure output of pump Milland line 98 with the engine oil pressure occurring in conduit 88. The governor is supported in a Well yknown manner outside of the propeller hub, as on a pad on engine V14 and is v'driven in the usual mannerifrom Vthe engine '14 'bythe gear 106. Line A98 from the 'gover- 'nor'is connected in a well-'known manner through transfer rings, riot shown, with the uid passage'6'6 -rotatable with propeller shaft 12. Line 104 is connected in a similar, well-known manner through transfer rings, not shown, with huid passage68 'rotatable with, and located in the interioroi lthe propeller shaft 12. These two passages t'and '68 are the only'fiuid lines leading to the propeller. P'assja-ge `68 leads iiito chamber 108 in valve vhousing yS6 which is connected lby a drilled passage 110 with the 'area `at the 'inboard side of piston B2. Passage 66 is connected "through orifice '112 with passage V114 and through orifice 116'in the valve cage118 to the interior nf the valveca'ge and `from thencetofthe interior of tube SG'leading to the "outboard side of the pitch changing piston 32. Hence it will be seen that ih one extreme p'os'ition of the governor -pilot valve, fluid under engine foil y pressure is maintained onohe sideof the piston and fluid Vunder high pressure is led to the vother 'side of the lpiston to move the piston in one direction and in the other extreme position of the governor 'pilot valve these Apressuresare reversed in their Vapplication lto the 4piston 'to move the ypiston in the otherdirection thus giving the double lactio'nto the governor and to the motor. The interior ofthe barrel is opento groove y120 which groove `is blocked from passage 114. by plug 122 and is connected bylpassage 12'4 with'groove 126 in valve cage 118. Valve cage 118 is Xed in valve housing56 and the groove 126 .is sealed from both the chamber 108 and the passages 1'1'4. Seals are also provided at the 'opposite end of the valve cage 118 sealing its connection with the tube 50 and the ljoint between the valve cage and the valve housing 56. A valve 128 having a 'stern 130 movable in a bore 132 ,in` valve cage 118 is urged by spring 134 onto a seat "1'36fin the valve cage 118. One end of spring 130 rests 4 onA the valve cage 118 and the other end rests on a washer y138 securedagainst outward movement by 'a pin '140. Groove 126 is connected by a passage 1'42 with a chamber 144 under the seat of valve v 128. The stern 130 of the valve `128 has one side iiatted to provide a passage 146 'connecting chamber k144 with chamber 148 at the inboard end oi the valvecage as shown in Fig. 2. From they above description it will be apparent that ,one 'side of.thefpistonisxalways connected through tube Si! to one side of valve 128 andthe other side of'the piston is always connected through-passage 110 to chamber 108 and the other side of the valve 128. Valve 128 is moved by a predominanceiofpressureon one side or theother soas .tofseatY valve128 on s eat 136 as shown in Fig. 2 orto move, the valve 'to the left until washer 138 contacts the hat surfaceon the inboard side of vvalve cage 118 as shpwninfig. 4. u

As shown in the drawings, with valve 128 seated on seat 1 36 the interior of the barrel is connected through line 3124, groove '126, kpassage 142, chamber 1.44, passage 146, chamber 148K, and chamber 108 with theiluid passage 68 and the governor outlet 104 whichin the overspeed conditions as shown is connected 'with line 88 ontainin'gfluid under engine oil pressure. Hence when fluid under pitch changing pressure is applied to the outboard 'side of piston 32, the interior of the barrel and the reap;` of thepiston are 'connected with engine oil pressure. When an underspeecl Vconditionoccurs and the pitch yisto bereduced, the -pilot valve 96, Fig. 1, will move downwardly connecting the line 104 withhigh pressure and the line 98 with engine oil pressure. Highpressure in line 1'0'4 is led through passage 68 -'to the inboard side of valve 128 forcing it to the left until washer 138 contactsthe inb'oardside of valve cage 118 as shown in Fig. 4. The inboard end 15o ofthe Hatred portiqnof stem'l() will thus bewithin bo're132. -Passage l'1"46 'will be blocked,thus sealing the chamber 144 of thevalve cage from chamber 148 and the high pressure which is led through passage to the inboard side of the piston 32. As previously indicated, this area at the inboard side of piston 32 is sealed from the interior of the barrel. Movement of the valve '128 to the left will move valve 128 oi of the seat 136 thus opening the chamber 144 to passages `11'4. The vinterior of the barrel is then connected throughppassages 124, vgroove 126, vpassages 41,42, and chamber 144 with 'orifices 116 and passages 114 which connect with the uid passage 66 in the lpropeller shaft which is connected through line 98 with the'e'n'gine oil pressure. Thus although high --pressure is applied to the rear ofv'p'iston 32, this high pressure is sealed from the interior of the barr'eland :the'pressiire on the interior of the barrel is limited to the engine oil pressure.

The above described structure provides a propeller having a double-acting hydraulic motor changing 'the propellenpitch with vonly two uid lines leading to the'propeller andL a valve mechanism actuated -by the pressure of the pitch changing fluid for blocking lthat iiuid from the `barrel interioryand simultaneously connecting the barrel interior with the drain side of the pitch changing ',rnotor. VAlthough we have described this invention as applied kto a spider` and split barrel type of propeller it is within the scope of the invention to'apply it to other types of propelilers suchiasnthe single piece barrel type shown in Patents Nos. 2,653,668 and 2,477,868.

While there has been described and illustrateda mechanical embodiment of what is now considered to be the preferred -form ofthe invention, it is to be understood that the invention is not limited to the construction so illustrated 'and described, but that such changes in size, shape and arrangement of parts may be resorted to as come within the scope of the subjoined claims.

.We claim:

, `l. In 'an aeronautical propeller having blades 'and a hub and a double-acting hydraulic pitch-changing motor carried by said hub and having interchangeable high and -lowf-pressure sides, means sealing the interior of said hub from saidxriotor, alpair of uid lines, lone line connected with one snide'of said motor and the other lineconnected with the other side of said rnotor, control mechanism outside saidhub and held against rotation with said hub and vconnected with both said lines and movable to direct uid to said lines to interchange said high and low pressure sides, a valve Vcarried by said hub, connected 'with both said lines and with the'hub interior and means operative responsive to movement of said control mechanis'r'nfor operatingusaid valveA to connect said hub interiorwith sailllow` pressure side. p l

2. j A device as claimed in claim l in which said control mechanism includes ,means connecting one lside of's'aid inotor with-hydraulic fluid under a predetermined'pressur'e and theopposite side V with hydraulic huid under a higher pressure, and means for reversing said connections,

p device'asclair'ned in claim 2 'inwhi'ch lthehydi'a'u.- lic .is "oiland in which the predetermined pressure is a substantially constant pressure. 4

L4. ,4A device'ras yclaimed in claim 2 in which the propeller is driven byan engine vhaa/ing a lubricating system,and in Rh'i'cii "Hy amic nd'is 'engine lubricating-bi1 and e errnnid pressure is "the engine lubricating 'system pressure.

5. in -an aeronauticalpr'opeller having yblades and n'a hub p and a doublelaotinghydralic pitch-changing rmotor ccarried-'by said hub-arid having interchangeable hi'ghrand low pressure sides, meanss'ealing the interiorof said hub I'fromsaid motor, apair of fluid lines, one line connected withone side -of'said motor k:and the other line connected `with the other side voi said motor, control mechanism "outside said' huband held `aga-inst rotation with said'hub 'andc'onnetetlwith"both said lines and movable'to direct 'Tli'd'to1saidlinesitointerchange said high andl low pres- `"sure""sid'e's, a valveicaried by said hub. y'c'o'nnectedwith both said lines and with the hub interior and means actuated by the fluid pressure in one line for moving said valve to connect the other line with the hub interior and actuated by the pressure in said other line to move said valve to connect said one line with the hub interior as the low pressure changes from one side of said motor to the other.

6. A device as claimed in claim in which said valve is a pressure actuated shuttle valve.

7. A propeller including a hub, blades mounted on bearings for pitch changing movement in said hub, a double-acting pitch changing rnotor connected with said blades, means for supplying fluid under pressure to said motor for moving the same to change the propeller pitch, a control valve for changing the application of pressure from one side to the other of said motor to change the direction of movement of said motor and a second valve, hydraulically connected with both sides of said motor, and having a connection with the interior of said hub, and actuated by said fluid pressure to automatically connect the interior of said hub with the side of said motor opposite to that receiving said fluid pressure to supply fluid to the interior of said hub and prevent the application of uid at motor operating pressure to the interior of said hub.

8. A propeller including a hollow hub, a cylinder having a closed end and an open end and secured at the open end to said hub, blades supported on bearings in said hollow hub, a piston in said cylinder mechanically connected with said blades for changing their pitch, means selectively supplying uid under pressure to one side or the other of said piston to increase or decrease the blade pitch, means, including a valve cage, sealing the hub interior from said cylinder open end, two lluid lines leading to said propeller, means permanently connecting one line with one side of said piston and the other line with the other side of said piston, valve means in said valve cage connected with said lines, said valve having a valve controlled connection between said lines and the interior of said hub and movable by a predominance of pressure in either line to block that line from the hub interior and connect the other line with the hub interior.

9. In an aeronautical propeller having blades and a hub and a double-acting hydraulic pitch changing motor carried by said hub, means sealing the interior of said hub from said motor, a pair of uid lines leading to said 6 propeller, one line connected with one side of said motor and the other line connected with the other side of said motor and a pressure actuaied shuttle valve having one side connected with one fluid line and the other side connected with the other fluid line and having a line controlled by said valve connecting the valve with the interior of said hub for connecting the interior of said hub with the low pressure side of said motor.

10. In an aeronautical propeller having blades and a hub and a double-acting pitch-changing motor carried by said hub and having interchangeable high and low pressure sides, means sealing the interior of said hub from said motor, a hydraulic control valve for said motor operable to selectively interchange the motor high and low pressure sides, a pair of fluid lines connecting said hydraulic control valve with opposite sides of said motor, and a second valve connected with both said lines between said control valve and said motor automatically connecting the interior of said hub with the line leading to the low pressure side of said motor.

l1. A device as claimed in claim 10, including means, actuated by the motor actuating pressure, moving said second valve to change the connection to the hub interior from one line to the other as the low pressure changes from one sidel of the motor to the other.

12. In an aeronautical propeller having blades and a hub and a double-acting hydraulic pitch changing motor carried by said hub, means sealing the interior of said hub from said motor, a valve connected with the hub interior and both sides of said motor and connecting the interior of said hub with the low pressure side of said motor and means actuated by the motor actuating pressure moving said valve to change the connection to the hub interior from one side of said motor to the other as the low pressure changes from one side of said motor to the other.

References Cited in the file of this patent UNITED STATES PATENTS 1,510,436 Englesson Sept. 30, 1924 2,300,233 Martin Oct. 27, 1942 2,379,302 Hoover June 26, 1945 2,462,932 Anderson Mar. l, 1949 2,573,783 Anderson et al Nov. 6, 1951 2,653,671 Martin Sept. 29, 1953 2,667,229 Allen Jan. 26, 1954 

